Circuit assembly encapsulated with polybutadiene urethane

摘要

An acceleration sensor is packaged in an open can and encapsulated in an elastomeric polybutadiene compound which maintains its mechanical properties over a range of -40 DEG C. to 105 DEG C. and transmits acceleration to the sensor with a unity transfer function. The encapsulation material comprises about 90 to 100 pbw of polyol and about 20 pbw of isocyanate, the polyol consisting of at least 70% of hydroxy-polybutadiene. For enhanced adhesion a foaming agent and/or an epoxy is added to the mixture.